7. Project Summary The long-term goal is to provide unprecedented 1000 frame per second angiography based on single- photon-counting detectors but with standard x-ray sources (a total capability presently unavailable to clinicians) to enable improved diagnostic and interventional patient care. The first set of specific aims include building and then physically testing this unique High Speed Angiography (HSAngio) system, enabling the evaluation of its performance on 3D printed phantoms to characterize detailed blood flow at reasonable radiation doses. The research design is to acquire larger 1000 fps single-photon-counting imaging detectors (Xcounter, by Direct Conversion) and, for a test biplane angiography system with standard x-ray sources, add these detectors so they can be brought, by a motorized changer, into the FOV for evaluation. A special contrast injector will be built and synchronized with the high speed image acquisitions. Images of both non-uniform contrast media globs and contrast labeled microsphere particles will be recorded to enable determination of flow streamlines and velocity distributions from the x-ray particle image velocimetry (X-PIV). These will result in determinations of wall shear stress and proper endovascular device function for use with the second set of specific aims to investigate the detailed flow patterns. These can be compared with those from the theoretical methods of computer fluid dynamics (CFD). Assessing the compromise between radiation dose and optimal dynamic imaging is also part of this set of specific aims. Finally, the third set of specific aims are to rigorously evaluate with our clinical collaborators the potential impact of the new availability of high temporal resolution imaging sequences quantitatively, semi-quantitatively and qualitatively of various procedures carried out on 3D printed patient-specific phantoms. We expect to rigorously test the HSAngio system on patient-specific pathological phantoms to evaluate the potential impact on clinical decision making primarily in neuro-endo vascular procedures such as treatment of and predictions for ischemic stroke due to vasospasm following hemorrhagic stroke. Finally, we will conclude by considering designs for future actual clinical implementation involving more advanced detector designs as well as the potential for wider applications such as to cardiovascular procedures. The results of this project should lead toward future clinical testing of this new imaging concept with the capability to vastly improve vascular image-guided interventional procedures by providing clinicians, even while treating the patient, to visualize for the first time the intricate details of blood flow that can be so crucial to the determination of clinical procedure outcome. We expect that, just as our previous high-spatial-resolution-detector NIH- funded project has been translated to practice, this HSAngio project will eventually become the standard state-of-the art in diagnostic and interventional imaging as well.